CONTROL OF STRUCTURAL AND ELECTRICAL PROPERTIES OF NANOGAPS USING FIELD-EMISSION-INDUCED ELECTROMIGRATION

We report a simple and easy method for the simultaneous control of electrical properties of multiple, integrated Ni nanogaps. This method is based on electromigration induced by a field emission current, which is the so-called "activation." The tuning of tunnel resistance of nanogaps was simultaneously achieved by passing Fowler-Nordheim(F-N) field emission current through three initial Ni nanogaps connected in series. Furthermore, the integration of single-electron transistors(SETs) was also achieved by simultaneously performing the activation for the series-connected nanogaps. Two simultaneously activated devices displayed Coulomb blockade properties, and Coulomb blockade voltage of each device was clearly modulated by the gate voltage. Hence, two SETs with similar electrical properties were successfully integrated by the activation procedure. These results indicate that the activation procedure is suitable for the simultaneous control of structural and electrical properties of multiple nanogaps and allows us to integrate planar-type nanogap-based SETs.(2)複数のナノギャップを直列に接続した集積型ナノギャップでのSET構造の一括作製・特性制御・集積化技術の開発:アクティベーションにより2つのSET構造の一括作製および集積化を達成した。集積した2つのSETはほぼ同一の特性を有し、アクティベーション条件によりナノギャップ系SETの素子特性を同時に制御・調節しながら、SETを集積化することが可能であることが明らかとなった。さらに、本手法において得られたラテラル型Ni/真空障壁/Ni系磁性トンネル接合単体でのトンネル磁気抵抗効果(TMR)から、室温にて10%程度のTMRの観測に成功した。

We report a simple and easy method for the simultaneous control of electrical properties of multiple, integrated Ni nanogaps. This method is based on electromigration induced by a field emission current, which is the so-called "activation." The tuning of tunnel resistance of nanogaps was simultaneously achieved by passing Fowler-Nordheim(F-N) field emission current through three initial Ni nanogaps connected in series. Furthermore, the integration of single-electron transistors(SETs) was also achieved by simultaneously performing the activation for the series-connected nanogaps. Two simultaneously activated devices displayed Coulomb blockade properties, and Coulomb blockade voltage of each device was clearly modulated by the gate voltage. Hence, two SETs with similar electrical properties were successfully integrated by the activation procedure. These results indicate that the activation procedure is suitable for the simultaneous control of structural and electrical properties of multiple nanogaps and allows us to integrate planar-type nanogap-based SETs.(2)複数のナノギャップを直列に接続した集積型ナノギャップでのSET構造の一括作製・特性制御・集積化技術の開発:アクティベーションにより2つのSET構造の一括作製および集積化を達成した。集積した2つのSETはほぼ同一の特性を有し、アクティベーション条件によりナノギャップ系SETの素子特性を同時に制御・調節しながら、SETを集積化することが可能であることが明らかとなった。さらに、本手法において得られたラテラル型Ni/真空障壁/Ni系磁性トンネル接合単体でのトンネル磁気抵抗効果(TMR)から、室温にて10%程度のTMRの観測に成功した。